Many conditions are characterized by disruptions in cellular pathways that lead, for example, to aberrant control of cellular processes, or to uncontrolled growth and proliferation of cells. These disruptions are often caused by changes in the activity of molecules participating in cellular pathways. For example, specific signaling pathway alterations have been described for many cancers. Despite the increasing evidence that disruption in cellular pathways mediate the detrimental transformation, the precise molecular events underlying these transformations have not been elucidated. As a result, therapeutics may not be effective in treating conditions involving cellular pathways that are not well understood. Thus, the successful diagnosis of a condition and use of therapies will require knowledge of the cellular events that are responsible for the condition pathology.
In addition, patients suffering from different conditions follow heterogeneous clinical courses. For instance, tremendous clinical variability among remissions is also observed in cancer patients, even those that occur after one course of therapy. Some leukemia patients survive for prolonged periods without definitive therapy, while others die rapidly despite aggressive treatment. Patients who are resistant to therapy have very short survival times, regardless of when the resistance occurs. While various staging systems have been developed to address this clinical heterogeneity, they cannot accurately predict whether an early or intermediate stage patient will experience an indolent or aggressive course of disease.
Accordingly, there is a need for a reliable indicator of an individual predicted disease course to help clinicians to identify those patients that will respond to treatment, patients that progress to a more advanced state of the disease and patients with emerging resistance to treatment.